"Oh, this expired two days ago," I say, wrinkling my nose as I inspect the yogurt. "I can't eat this."

"It's unopened!" my husband replies. "It's fine."

"No, no. It's expired. I don't want to get sick!" And with that, I dramatically toss the spoiled yogurt -- and $2 -- into the trash.

Who's right? Well, I am unhappy to type this, but according to food researchers, my husband is -- for the most part -- correct. I've been wasting a bunch of perfectly edible food for years.

That's because expiration dates aren't really an indicator of expiration at all. The date merely indicates when the food's quality will begin to diminish. Eating week-old bread isn't necessarily dangerous; your sandwich just might not be as soft and moist.

Manufacturers use sell-by or best-by dates on their products so grocers will know how long to display the product for sale. This protects the manufacturer's reputation as a creator of delicious, tasty foods.

Sell-by and best-by dates are not ‘safety dates.' As long as you've stored the unopened product properly, you can probably eat it well beyond the printed date. For example, according to the U.S. Department of Agriculture, eggs are "perfectly safe to eat… three to five weeks of the date you purchase them," regardless of the carton's sell-by date.

Use-by dates also relate to food quality; this date is set by manufacturers and indicates when the food's freshness will pass. You most often see use-by dates on poultry and meat. The USDA states that "even if the date expires during home storage, a product should be safe, wholesome and of good quality if handled properly and kept at 40 degrees Fahrenheit or below."

The upshot is that sell-by and use-by dates mean very little. That does not, however, give you license to eat expired food with abandon. Instead of looking at the calendar, simply follow your eyes and nose. Food will last within a reasonable timeframe.

For meat and milk, give it the old sniff test, and if it's got a funky odor, or has an odd color definitely do not eat or drink it. But if it looks and tastes fine, it's probably safe to eat it past the expiration date, according to the food safety experts at the USDA.

There's one notable exception to this rule -- infant formula. Federal law requires that manufacturers of infant formula put a use-by date on formula. It's important to follow this date because expired infant formula can clump, making it hard for your baby to suck the milk through the bottle's nipple. Additionally, nutrient quality of the formula diminishes over time, so your baby may not get enough of a certain vitamin or mineral if he is consuming expired formula.

Caitlin Boyle is a professional blogger, motivational speaker, and author of the book Healthy Tipping Point: A Powerful Program for a Stronger, Happier You. She helps her husband run a holistic health clinic in Charlotte, North Carolina.

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